Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Grand Forks ND
1016 am CST Friday Dec 19 2014
issued at 1015 am CST Friday Dec 19 2014
Satellite and observation Show Low clouds and fog (mostly 1-3sm type) over
the forecast area. Light freezing drizzle as well in many spots...but
quite light and so far not a travel concern. Some low level drying
may move into southwestern forecast area from Bismarck area this afternoon
but otherwise fail to see any change so expanded fog/freezing
drizzle mention into the afternoon for most areas. Area of light snow
in Baudette-Waskish area will continue into early afternoon.
Short term...(today through saturday)
issued at 315 am CST Friday Dec 19 2014
Forecast challenge will be precipitation chances and temperatures. Models
in fair agreement and will use blend with no real model preference.
Upper low over S mb will drift east next 24 hours. Lead
impulse/shear axis over northwest Minnesota will lift NE this morning with secondary
wave over the western Dakotas moving in later today. Radar returns
associated with lead impulse lining up nicely with isentropic lift
from k285 surface. Condensation pressure deficits do lower through
the morning and with current visibility under snow band briefly dropping
below 7 miles feel there could be some measurable snow fall so
increased probability of precipitation to cover brief heavier snow showers. Behind this
band not much happening as far as precipitation. As lower ceilings push east
cannot rule out some flurries so maintained mention. No reports so
far of fzdz however there is some potential during the day so will
will have to monitor this. Warm advection will be off set by cloud
cover however with warmer start temperatures should be able to
recover above average.
Kept low end probability of precipitation over the NE tonight as weak lift and lower
condensation pressure deficits continue. Temperatures to remain
mild with coolest readings over the northwest forecast area where some decrease in
clouds is possible.
Short wave ridging builds in for Saturday so will keep forecast
dry. Temperatures will hinge on clouds however with relatively
warm column temperatures to remain mild.
Long term...(saturday night through thursday)
issued at 315 am CST Friday Dec 19 2014
Next wave to impact forecast area Saturday night into Sunday will be
accompanied by weakening surface reflection so continued with low
end probability of precipitation. Confidence low on freezing precipitation potential however with
some drying in the middle levels late there may be some areas of fzdz
so kept in the forecast. Temperatures to stay mild.
Monday-Thursday...model solutions indicate several upper shortwave
troughs will help to amplify a broader upper trough over the
north-central US early next week. The 00z GFS/European model (ecmwf) eventually
indicate stronger cyclogenesis over the Great Lakes middle-week as the
upper level energy consolidates. However...before the
happens...uncertainty exists as to the position of embedded
shortwave troughs...and associated surface features over the
northern plains/upper Midwest. Would expect at least some light
precipitation over the region Mon/Tue...but location will hinge on the
evolution of the upper level low. Models then differ on the speed of
the eastward progressing low pressure system and approaching Pacific
energy from the west late in the period...leading to low confidence.
Temperatures overall will be seasonably mild through early week...with at
least some degree of cooling by late in the period.
Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 633 am CST Friday Dec 19 2014
IFR ceilings from Valley West and will likely continue to spread east
through the morning. Some slight improvement possible this
afternoon however at best some parts of the region may get in MVFR
conditions. Also some MVFR/IFR visibility from Valley West which may
also improve by afternoon.